package reflect;

import java.lang.annotation.*;
import java.lang.reflect.Field;
import java.lang.reflect.Type;

public class Test09 {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchFieldException {
        Class c1=Class.forName("reflect.Student2");
        //通过反射操作注解
        Annotation[] annotations=c1.getAnnotations();
        for(Annotation annotation:annotations){
            System.out.println(annotation);
        }
        //获得注解的value值
        TableHalo tableHalo=(TableHalo)c1.getAnnotation(TableHalo.class);
        String value=tableHalo.value();
        System.out.println(value);
        //获得指定类属性的注解
        Field f=c1.getDeclaredField("name");
        FieldHalo annotation=f.getAnnotation(FieldHalo.class);
        System.out.println(annotation.columnName());
        System.out.println(annotation.type());
        System.out.println(annotation.length());
    }
}
@TableHalo("db_student")
class Student2{
    @FieldHalo(columnName = "db_id",type = "int",length = 10)
    private int id;
    @FieldHalo(columnName = "db_age",type = "int",length = 10)
    private int age;
    @FieldHalo(columnName = "db_name",type = "String",length = 3)
    private String name;
    public Student2(int id, int age, String name) {
        this.id = id;
        this.age = age;
        this.name = name;
    }
    public Student2() {
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}
//类名注解
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@interface TableHalo{
    String value();
}
//属性注解
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@interface FieldHalo{
    String columnName();
    String type();
    int length() ;
}